Often, sheet metal parts are manufactured to include certain marks, such as company logos, part numbers, dates (e.g., the date of manufacturing), material information, symbols for mounting, and/or other marks. When manufacturing sheet metal parts using a punching press, the marks may be applied to the part by the punching press itself.
The sheet metal parts can be marked by a hob having a shape corresponding to the desired embossed mark to be applied to the part, and the mark can be impressed in the sheet metal by a single machining stroke. However, since this process for applying marks can consume a significant amount of operating time of the hob used to apply the desired mark, flexibility can be limited.
Another way to apply a mark to a sheet metal part is to impress a series of dots (e.g., a grid of dots) in a desired pattern to create the appearance of the desired mark. The pattern of dots can be applied dot by dot using a marking pin to imprint the sheet metal. Typically, the dots are separated by distances small enough that the desired pattern appears as a line or a web. In order to create a pattern of dots that appear as a web, it can be necessary to imprint a large number of dots into the sheet metal.
These processes of applying marks to sheet metal parts generally involve a stamp having a tapered tip disposed in an upper tool holding fixture. The upper tool holding fixture is typically oscillated by an upper tool holding fixture drive. When the tip impinges on the surface of the sheet metal, a dot-shaped indentation having a depth of few tenths of a millimeter is indented in the metal sheet. The frequency of the strokes is typically limited to 2800 to 3000 strokes/minute by conventional drive techniques due to the high masses of the drives.